This invention concerns a circuit arrangement for a driving motor, especially a wiper motor, comprising a controllable switching element for switching a motor operating circuit, said switching element being controllable by a manually actuable operating switch and by a disconnection signal of a limit switch.
In a known circuit arrangement of this type a relay serves as a controllable switching element the changeover contact of which alternately closes the motor operating circuit or a motor short circuit. The winding of said relay in connection series with the operating switch is directly connected to the supply voltage. In parallel to the operating switch a limit switch operating as a circuit-breaker is located, through which the relay is kept in operating position also with switched off operating switch for so long, until the wiper driven by the motor has reached a parking position. The relay can thus be switched off by a disconnection signal of the limit switch, which is conducted through a separate control lead. From the switch to the driving motor of this known type thus two cables have to be layed, namely on the one hand the motor supply lead and secondly a control lead through which the disconnection signal of the limit switch is conducted to the controllable switching element. This circuit arrangement is therefore very expensive, especially if -- as it is for instance the case with rear window wiping installations of automotive vehicles -- the switch is located remote from the driving motor. Then quite a lot of cable material is required for the supply lead and for the control lead which entails corresponding costs, whereby it has also to be considered that it is always connected with difficulties to place a lead additionally into an available cable conduit of an automotive vehicle.
These disadvantages are avoided, according to the present invention, as the disconnection signal of the limit switch is directly conducted to the switching element through the motor current supply cable.